Synthesis of Enantioenriched trans‐Fused Bicyclo[4.4.0]‐ dec‐3‐enes and Bicyclo[4.3.0]non‐3‐enes Bearing a 1,5‐Lactone Bridge

Abstract

The combination of (À)-sparteine-mediated lithiation of (2-methyl-cyclohex-1-enyl)methyl or (2-butyl-cyclopent-1-enyl)methyl carbamate and enantioselective homoaldol reaction with acrolein, transformation to a g-lactone, enolate allylation, followed by a ring-closing olefin metathesis provides a facile entry to tricyclic lactones of type 7, bearing a 1,5-lactone bridge.